Project Blue Book Special Report No. 14: Analysis of Reports of Unidentified Aerial Objects

Special Report No. 14 was issued by the U.S. Air Force's Air Technical Intelligence Center on 5 May 1955. It is a statistical study of about 4,000 reports of unidentified aerial objects from June 1947 to December 1952. The reports were reduced to IBM punched cards and analyzed with methods including chi square tests. The report concludes that the reports it examined are very unlikely to represent technology beyond present scientific knowledge, and it notes that no case produced valid physical evidence.

TABLE V CHI SQUARE TEST OF KNOWNS VERSUS UNKNOWNS
ON THE BASIS OF DURATION OF OBSERVATION
Duration of
Observation
5 sec or less
6-10 sec
11-30 sec
31-60 sec
61 sec-5 min
6-30 min
Over 30 min
Not stated
Number of
KNOWNS
259-"
92
153
108
269'
305
135
444
Adjusted
Number of
KNOWNS (K)
64
23
38
26
66
75
33
109
Number of
UNKNOWNS (n)
27
21
33
42
99
71
3 7 l
104
X 2
(K-n)2
K
21.39
0. 17
0.66
9.85
16. 50
0.21
. 0.48
0.23
Total 1765 434 434 49.49
# Degrees of freedom
5%
1%
14. 1
18. 5
65
it I